The invention is directed to a method of waterproofing roofs and the like. In particular, the invention concerns a waterproofing method wherein a continuous impervious membrane is formed upon roofs and the like, the membrane being spaced from the roof to permit movement of moisture and further being constructed using factory-prepared, flexible sheet-like laminates of the type having a self-adhesive bituminous waterproofing layer supported by and adhered to a sheet support therefor, such as plastic film or foil.
Roofs and like building surfaces exposed to the weather must in some fashion be provided with a continuous layer impermeable to water, a so-called "waterproofing membrane". For many years (and still today) the most common "membrane" is comprised of several plies of asphalt-impregnated felts bonded together with hot or cold-applied asphalt, tar, etc., adhesive. The bonding of the several plies together is usually accomplished in situ upon the roof, hence the terminology "built-up waterproofing membrane".
Flexible sheet-like laminates of (a) support films and (b) self-adhesive bituminous waterproofing layers pre-formed in the factory have been successfully employed in roofing and other waterproofing applications as substitutes for the aforedescribed "built-up" waterproofing membranes which are constructed at the job site by plying together one or more layers of bitumen-saturated paper or felt and usually hot bituminous adhesives. The pre-formed, self-adhesive laminate-membranes offer many advantages including factory controlled preparation, avoidance of heating equipment and handling of hot materials at the job site, as well as many performance advantages.
Flexible pre-formed laminates of the aforementioned type and their use to form waterproofing layers in various kinds of building structures are described for example in U.S. Pat. Nos. 3,741,856; 3,853,682; and 3,900,102 to John Hurst. Such patents describe in particular the preparation of flexible laminates containing a support material, for example a layer of a polymeric or metallic film non-removably joined to a layer of self-adhesive, or pressure-sensitive adhesive, bitumen-elastomer waterproofing composition. As discussed in particular in U.S. Pat. No. 3,900,102, such laminates may ideally be constructed in the plant in the form of a roll with a protective sheet, for example a sheet of siliconized paper applied against the self-adhesive bituminous waterproofing layer, transported to the job site, and thereafter applied to a substrate bituminous adhesive side down, each successive laminate strip being made to overlap the edge of the previously-applied strip of laminate to insure a continuous waterproofing seal.
Commercial products produced utilizing the basic technology of these patents and designed particularly for roofs are described in brochure 7.1/Gr. entitled "CRM.sup..RTM. Self-Adhesive Roof Systems", published by W. R. Grace & Co., 1980. As described in such brochure, the exposed surface of the support sheet of the applied membrane is given a final smooth surface protective coating or a coating of adhesive to bond subsequently-applied weathering material such as gravel.
In certain roofing applications, it is necessary or desirable that the waterproofing membrane layer not be adhered over its entire lower surface to the roof substrate or deck as in the case of the aforementioned patents and brochure. For example, many roofing systems incorporate as the, or as part of the, thermoinsulation in the roof, one or more layers of lightweight cementitious thermoinsulating concretes. Such concretes typically comprise mixtures of essentially a hydratable cementitious binder such as Portland cement or gypsum, and lightweight low-density aggregate. Chemical additives such as surfactants may further be present to entrain air, etc. The concretes are usually prepared at the job-site by mixing water with the dry ingredients, pumping the wet mix to the rooftop, casting the wet concretes upon the roof and thereafter allowing the concrete to hydrate or dry. Moisture remaining in such concrete layers after installation of the waterproofing membrane thereover can become a problem on hot days in that the heat could cause blistering within the membrane. To avoid this, the waterproofing membrane is spaced from the roof deck which allows room for movement of moisture beneath the membrane. To provide the necessary bonding of the membrane to the roof and increase its resistance to being "uplifted" by wind, the membrane is "spot-bonded", e.g., adhered to the deck by spaced-apart roofing nails which leave sufficient space beneath the membrane for moisture movement.
In adapting the self-adhesive waterproofing membrane laminates of the type shown in the aforementioned Hurst patents and "CRM" product brochure to roofing systems requiring spacing between the membrane and the roofdeck, a separator sheet is necessary to negate the adhesion between the self-adhesive bituminous layer and the roofdeck. Also, to hold the "weathering" layer of gravel finally applied to the surface of the membranes, a coating of gravel adhesive must first be applied (c.f. page 305 of the aforementioned "CRM" product brochure). The gravel, inter alia, protects the upper plastic film support from ultraviolet radiation.The use of such separator sheets and application of such gravel adhesive after installation of the membrane laminates however lead to increased costs of labor and material and also slow the installation rate of the waterproofing membrane system.
Pre-manufactured waterproofing membranes comprised of polymer film layers and bituminous waterproofing layers have been applied in the past to roofs, etc., in a manner such that the membrane is not adhered over its entirety to the roof. For example, a pre-manufactured membrane laminate termed "KMM" and described in a product brochure entitled "KMM Koppers Roofing and Waterproofing Membrane", published by Koppers Company, Inc., 1976, is applied in such a "floating" or "loose-laid" fashion. The "KMM" product is a non-self adhesive, multi-layer laminate comprised of several layers of plastic film and bitumen composition which is laid upon the roofdeck and abutting edges of like laminates are heated to "weld" the laminates into a continuous waterproofing layer. Also, in U.S. Pat. No. 4,039,706 to Tajima (1977), self-adhesive strip-laminates comprised of a sheet support and self-adhesive bituminous layers are said in one embodiment (column 11) to be applicable to roofs, etc., adhesive-side up. Another like laminate is then applied adhesive-side down to the upper exposed layer of adhesive of the first applied laminate resulting in a continuous waterproofing membrane layer composed over its entirety of "multi-layers" of bituminous adhesive and sheet support.